1. Field of the Invention
The invention relates to automated test and measurement instruments which utilize a microprocessor controlled user interface, and more particularly to a system for simultaneously probing a circuit while remotely controlling test and measurement instrumentation used for the probing.
2. Description of the Prior Art
Automated test and measurement instruments such as digital storage oscilloscopes utilize a digital display for portraying digitized waveforms, test parameters, settings, and cursory readouts. The display achieved corresponds to an input signal as well as to certain user interactions to the test and measurement instrument. For example, a person working with a test instrument may depress certain control keys provided for the instrument in order to achieve a specific result, such as movement of a cursor or the adjustment of a calibration or measurement gradient. In oscilloscopes, for instance, a specific measurement may require the user to change the time base or magnification setting; these changes require manipulation of the controls on the oscilloscope as well as those exhibited on the instrument's display.
The development of control switches for test and measurement instrumentation has traditionally followed a single path. As those skilled in the art are aware, historically, the control switches for a device resided on the face of the measurement device. The user was forced, when he or she desired to manipulate the control settings, to stop the actual act of measuring or testing and make the required adjustments. In many cases these adjustments demanded the user to remove the measuring probe from the tested circuit because the user's hands were required for the test instrument control switch manipulation. Removal of the test probe often slowed down the test process as it may take considerable time to repeatedly locate the proper test point and make a proper electrical contact. Thus, whenever the test probe had to be removed the test process was slowed. Consequently, the prior art control switches located on the face of the test and measuring equipment create significant obstacles to the efficient, accurate and rapid testing of devices.
Recently, prior art test and measurement instruments have incorporated more "user friendly" interface and control technology. These more advanced prior art interfaces employ less, and some times no, hardware buttons on the front of the instrument. Instead of hardware buttons and switches, these prior art devices utilize multiple "soft buttons." The "soft buttons" are graphically drawn on the instrument's display. Because they are not "hard wired" buttons, the user does not necessarily have to physically manipulate the button. Instead, they may be controlled and activated by a pointing means such an arrow key, knob, or a mouse. Once selected, the function associated with the selected "soft button" becomes activated. In many instances, activating one soft button function could result in a number of other soft button options associated with the first button to become active. Thus, a series of selections may be effectuated through the initiation of a single "soft button."
While the newer "soft buttons" provide additional flexibility, they continue to have their drawbacks. For example, one major problem with these new test and measuring instruments continues to be that they require the user to free at least one hand to make the desired adjustments, even by way of a mouse. Consequently, the user has no way to change settings or make arbitrary cursor adjustments without the use of a free hand while probing a circuit. As it is often desirable to make the changes and adjustments simultaneously while probing a test point on a circuit, a free hand may not be readily available. It is very frustrating and time consuming to release the test probe from the test point so that settings and cursor measurements can be made. This problem arises resoundingly when probing VLSI chips having one hundred or more pins.
Consequently, there is a need for a probe that incorporates control capabilities over the measurement and test instrumentation being employed. While a number of buttons or cursor keys could be implemented along a probe's grip, the use of such buttons would demand a very dexterous finger to press the correct button for the desired function. Additionally, the user may sever his or her test point as he or she attempts to manipulate the control buttons located on the probe. Thus, a need exists for a test probe and system which can adjust and manipulate the calibration and measurement settings of a test instrument, while the probe is in use. The test probe should be operable without the use of buttons or cursor keys so that the user need not release or change his or her grip on the probe.